Rotating brake disc subassembly with segmented beryllium core

ABSTRACT

BRAKE DISCS WHICH HAVE A PAIR OF ANNULAR STEEL PLATES AND SEGMENTED BERYLLIUM FILLER PLATES BETWEEN THE ANNULAR STEEL PLATES. THE STEEL PLATES HAVE SINTERED METALLIC OUTER FACES AND ARE RIVETED TOGETHER ON OPPOSITE SIDES OF THE BERYLLIUM PLATES. THE BERYLLIUM FILLER PLATES EXTEND FROM THE CENTER OF ONE KEY SLOT TO THE CENTER OF THE ADJACENT KEY SLOT AND EACH OF THE FILLER PLATES IS SLOPED AT ITS OUTER END SO THAT THE ADJACENT FILLER PLATES DEFINE A VSHAPED NOTCH CENTERED WITH THE KEY SLOT. TRIANGULAR STEEL INSERTS ARE RIVETED TO THE STEEL PLATES AT THE KEY SLOTS. THE TRIANGULAR INSERTS SERVE TO TRANSMIT TORQUE ACROSS A BROAD AREA TO THE BERYLLIUM FILLER PIECES BY WEDGING ACTION BETWEEN THE SIDES OF THE INSERTS AND THE SLOPED PORTIONS OF THE FILLER PLATES.   D R A W I N G

Feb. 27, 1973 .1. F. DERNOVSHEK ET AL 3,718,210

ROTATING BRAKE DISC SUBASSEMBLY WITH SEGMENTED BERYLLIUM CORE Filed Junb 24, 1970 Amara. a

Q76 mvemoas 4 JOSEPH F. DERNOVSHEK PETER 0. BIRMlNGHAM 74 BY: FlG.-3 w 2: (2 g United States Patent 3,718,210 ROTATING BRAKE DISC SUBASSEMBLY WITH SEGMENTED BERYLLIUM CORE Joseph Frank Dernovshek, Akron, and Peter D. Bermingham, Sutfield, Ohio, assignors to The Goodyear Tire & Rubber Company, Akron, Ohio Filed June 24, 1970, Ser. No. 49,242 Int. Cl. F16d 65/12 US. Cl. 188-218 XL 13 Claims ABSTRACT OF THE DISCLOSURE Brake discs which have a pair of annular steel plates and segmented beryllium filler plates between the annular steel plates. The steel plates have sintered metallic outer faces and are riveted together on opposite sides of the beryllium plates. The beryllium filler plates extend from the center of one key slot to the center of the adjacent key slot and each of the filler plates is sloped at its outer end so that the adjacent filler plates define a V- shaped notch centered with the key slot. Triangular steel inserts are riveted to the steel plates at the key slots. The triangular inserts serve to transmit torque across a broad area to the beryllium filler pieces by wedging action between the sides of the inserts and the sloped portions of the filler plates.

The present invention relates to brake discs and more particularly to said discs which employ beryllium heat sink fillers.

The use of heat sink filler plates in brake discs is well known as is the use of beryllium plates for this purpose. However, the earlier brake discs employing beryllium filler plates have relied entirely on the steel discs to transmit the braking torque and as a result the steel discs must be relatively heavy to withstand the forces transmitted.

While beryllium possesses characteristics of high specific heat and thermal conductivity together with low density which makes it suitable for use as a heat sink material, it also possesses lo'w structural characteristics especially at higher temperatures and as a result cannot be subjected to large thermal or structural stresses. In the brake discs of the prior art, the beryllium filler plates have been utilized solely as heat sink members and the steel plates relied upon to transmit all of the torque forces encountered during braking. This arrangement, however, requires the use of heavy steel plates increasing the weight of the brake discs.

It is the principle object of the present invention to provide a brake disc having a beryllium filler plate and steel face plates which in total is of lighter weight than the discs of the prior art.

It is also an object of the present invention to provide a brake disc having beryllium filler plates in which the beryllium filler plates may be reused when the steel plates have become worn.

As will become apparent from the following specification, the objectives of the present invention are accomplished by providing a disc assembly which consists of two steel plates having sintered metallic wear faces and beryllium filler plates carried between the steel plates. The invention contemplates the use of triangular metallic inserts at the key slots of the disc to transmit a portion of the braking torque between the beryllium segments and the keys in such a manner that the segments while subjected to forces are not subjected to excessive stresses.

For a more complete understanding of the invention reference should be had to the following specification and accompanylng drawings wherein there is shown a preferred embodiment of the invention.

3,713,210 Patented Feb. 27, 1973 ice In the drawings:

FIG. 1 is a fragmentary side elevational view of an aircraft disc constructed in accordance with the present invention;

FIG. 2 is a fragmentary sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary side elevational view of a modified brake disc also constructed in accordance with the principles of the present invention; and

FIG. 4 is a fragmentary sectional view taken along line 44 of FIG. 3.

Referring first to FIGS. 1 and 2 there is shown a portion of a brake disc which includes a pair of annular steel plates 10 and 12 which have sintered metallic outer faces 14 and 16, respectively. Each of the plates 10 and 12 forms a complete circle. Beryllium filler plates 18 are received between the steel plates 10 and 12 and each filler plate extends along a 60 segment of the brake disc.

Each of the annular steel plates 10 and 12 has notches 20 on its outer circumference uniformly spaced at 60 intervals along the discs. These notches or slots 20 receive keys or straight splines on the underside of the wheel rim (not shown) so that the discs rotate with the wheel. The key or splines actually engage steel inserts 40 to be more fully explained hereinafter. The discs 10 and 12 are also provided with deep U-shaped slots 22 at uniformly spaced intervals along their inner circumferences to allow for expansion of the disc without warping or distortion.

In the preferred embodiment each of the beryllium filler plates 18 extends from the radial center line of one of the slots 20 to the radial center line of the adjacent slot 20. The discs 10 and 12 and filler plates 18 are secured together by rivets 24 which pass through steel bushings 26 received in holes 28 of the filler pieces 18. The ends of the bushings 26 are cambered as indicated at 30 and the steel plates 10 and 12 are bent inwardly as indicated at 32 to conform to the cambered ends of the bushings 26. This arrangement of the cambered edges and the steel bushings 26 assures a uniform clamping of the steel plates 10 and 12 to the beryllium filler pieces 18 and prevents excessive concentration of forces around the edges of the holes 28 in the beryllium plates 18. Further, it allows the head of rivet 24 to remain below the rubbed surface of plates 10 and 12. There are two features of the bushings 26 that are important to the objects of the invention. First, the bushing 26 achieves a proper projected area to allow the beryllium core pieces to take torque and secondly it allows a small size rivet and head to be used so there is no projection above the rubbed surface of the outer plates. It is important that the bushing 26 have a clearance with the core piece of not more than .020 inch so the fit is not sloppy, but not less than .003 inch so that expansion of the bushing 26 will not cause a hooping effect and crack the beryllium itself. The projected area of the bushing 26 is critical to achieve the proper torque loading of the core pieces without failure. The projected area is defined herein as the outside diameter of the bushing times the length thereof, with this product being in square inches. The invention contemplates that the projected area loading must not be greater than 6,000 p.s.i., and for the purpose of obtaining the best heat sink capability for the material should not be less than 1,000 p.s.i.

The ends of the beryllium filler pieces have straight portions 34 which are parallel to the radial center line of the notch 20 and upper portions 34 which are inclined 60 to the radial center line of the notch 20. Thus, adjacent filler plates 18 define a V-shaped notch 38 centered with the notch 20. Steel inserts 40 are attached to the annular steel plates 10 and 12 by rivets 4-2. These inserts have lower edges 44 which extend at 60 to the radial center line of the notch 20 and, thus, parallel to the sloped edges 36 of the beryllium core pieces 18. The steel inserts 40 also have notches 46 on their outer surfaces to engage the keys or splines of the wheel. The notches in the plates 10 and 12 are cut back somewhat as indicated by line 21 in FIG. 1 so the keysor splines only engage the notches .46 of the inserts 40. As will be seen inFIG. 1, adjacent edges 34 of the beryllium cores are separated from one another by short distances as are the adjacent edges 36 of the cores and the edges 44 of the steel inserts 40 to give some fabrication-tolerance and allow the cores to somewhat float in their laminated relationship between the plates 10 and 12.

Preferably, the angled orinclined portions 36 of the filler pieces 18 and the inclined edges 44 of the inserts 40 are at angles of between 50 to 70 relative-to a radial, with 60 being optimum. The depth of the angles or the V-notches 38 of adjacent pieces 18 should be between to 60% the face width of the beryllium pieces. We

mean the distance indicated by line L inFIG. 1 as the face width. The cooperating inclined surfaces 36 and 44 at such critical angular relationship must comprise a minimum of 30% of the inclined distance. The inclined distance is defined as the full distance from the base of the V-notches 38 along the critical angle to the edge of the respective filler piece 18 and insert 40. Hence, it should be understood that the pieces 18 could take various geometric configurations as long as sufiicient cooperating relationship is achieved along the critical angle with the respective insert 40.

The annular steel plates '10 and 12 are also provided with notches 48 along their outer circumferencee which serve to prevent bending of the disc assembly-or uneven transfer of torque between the steep plates 10 and 12 and end portion 62 are heldbetween steel plates 66 and 68, each of which is in the form of three 120 segments of an annular ring. Eachof the plates 66 and 68 has a pair of notches 70 on its outer circumference located 30 from the end of the plate and 60 from one another. One of the beryllium filler pieces 60is positioned between each of the notches 70. Opposite ones of the beryllium filler pieces 60 span the ends of the adjacent steel plates 66 and 68.

Each of the plates 66 and '68 is provided with a deep U- shaped notch 72 extending radially outward from the inner circumference of the plate midway between the ends thereof. The radially inward portions of the ends of the plates are also notched to provide U-shaped notches 74 between adjacent plates 66 and 68.

The steel plates 66 and 68 and the beryllium filler Pieces 60 are secured to one another by rivets 76 which pass throughbushings 78 in the beryllium plates 60. As in the previously described embodiment, the ends of the bushings are cambered and'the plates 66 and 68 bent inward- 'ly as indicated at 80, to correspond to the cambered edges of the bushings 78. The outer circumferences of the steel plates 66 and 68 between adjacent notches 70 of the same plate are notched as shown at 82. These notches are the uniform radius and leave a portion 84 of the plate which receive rivets 86 serving to further secure the plates 66 and 68 and the beryllium core 60 as a unit. A notch 88 is also provided in the outer circumference in each of the plates 66 and 68 between the notch 70 and the end of the plate. These notches 80 are of uniform radius, but ar smaller than the notches 82 to provide end portions 90 at each end of the plates 66 and 68. Rivets 92 are provided i he end port o 0 9 ea P e.

As in the previous embodiment, steel inserts 94 are secured by rivets 96 to the plates 66 and 68 at the notches 70 and these inserts havesloped inner edges 98 Which extend parallel to the sloped edges 64 of the tiller plat s 60. The inserts 94 also have notches 100 aligned With the notches 70 of the steel plates 66 and 68. Preferably, the relationship between the notches 70 and 100 is the same as between the notches 2'0 and 46 defined above.

In either of the embodiments described, the torque transmitted betweenthe beryllium filler pieces and the steel inserts is transmitted alongthe broad area of contact between the sloped edges of the filler plates andthe correspondingly sloped edges of the steel inserts. As a result, the torque is transmitted-by wedging action and is applied uniformly over a substantial area of the beryllium plate to preventexcessive stressing along a small region. The rivets.24 and 76because of the cambered insert further serve to transmit torque between-thesteel plateand the beryllium core.

While the angle between the steel inserts and the beryllium core pieces is illustrated as being about a 60-120 relationship, it should beunderstoodthat this relationship might vary between about 5070; 100 and still meet the objects of the invention.1Furthcr, while the radial depth of the steel insert relative to the beryllium core pieces as iluustrated as being /3 the radialdepth, to give the best heat sink/weight, torque transfer ratio, it should be-understood that the radial depth'could vary by about 20% to the radially outward side and by about 50% to of the invention have been described, the invention is not so limited and changes or additions can be made thereto without departing from the essence thereof. Reference should therefore be had to the following claims in detenmining the true scope of the invention.

Whatis claimed is:

1. A brake dsic assembly for a Wheel brake, comprismg:

a pair of steel plates each in the form of an annular ring having internal and external circumferences and a plurality of pairs of lugs projecting from one of the circumferences in the plane of the plate, the lugs of each pair being spaced apart uniformly and the pairs being located at uniform angular intervals;

a beryllium core assembly between the pair of plates,

the core assembly consisting of a plurality of beryllium segments, each segment extending between the radial centerlines of adjacent pairs of lugs, the ends of adjacent segments being slanted to define V-shaped notches at the radial centerlines, the portions of the segments between adjacent pairs of lugs projecting beyond thecircumference of the plates, the opposite sides of the segments being coincident with the other circumference of the plates;

rivets passing through the plates and the segments to secure the plates to the segments;

a plurality of steel inserts, one insert being located at each pair of lugs, having a notch aligned with the space between the lugs of the'pair and having surfaces complementary to and closely adjacent the slanted portions-of the segments; and

additional rivets extending through the lugs and the inserts for securing the inserts to the steel plates.

2 The brake disc assembly according to claim 1 Whereprising:

in additional lugs are provided on the steel plates, one additional lug being provided between each pair of lugs and overlying the projecting portions of the core segments, additional rivets passing through the additional lugs and the projecting portions of the segments to secure the lugs to the segments.

3. A brake disc assembly for a vehicle comprising:

an annular core formed of a plurality of equal size beryllium core pieces, the outer portions of the ends of each core piece being slanted so that adjacent core pieces define notches having at least a portion thereof defining an inclined surface,

steel plates forming annular rings on each side of said core;

rivets passing through steel bushings in said core pieces and securing said core pieces and said steel plates as a unit; and

metallic inserts secured to said plates at said notches,

said inserts having inclined surfaces shaped to directly cooperate with the inclined surface of said notches defined by said core pieces, and including a formed portion designed to cooperate with said vehicle wheel for carrying torque, whereby partial torque transfer is through said core pieces between said inserts and said steel plates.

4. The assembly according to claim 3 wherein one por- 5. The assembly according to claim 4 wherein three steel plates form the annular ring on each side of said core, the ends of each steel plate being at the middle of one of said core pieces and aligned with the ends of the steel pieces on the opposite side of said core.

6. A brake disc assembly, for a vehicle wheel coma beryllium core in the form of an annular ring consisting of a plurality of beryllium core pieces, the ends of each core piece having one portion in parallel abutting face to face relation to the same portion of the adjacent core piece and a second portion inclined from the one portion, whereby adjacent core pieces define a V-shaped notch;

steel plates on each side of said beryllium core, said steel plates forming annular rings;

rivets securing said steel plates and beryllium core as a unit; and

metallic inserts secured to said steel plates at the V- shaped notches defined by said core pieces, said inserts having inner edges arranged complementary in direct abutting face to face relation to the inclined edges of said core pieces to effect torque transfer 55 6 through said edges, and a notch on the outer edge to receive the key of the vehicle wheel.

7. The brake disc assembly according to claim 6 wherein said beryllium core consists of six equal size core pieces, and the steel plates are cut away around the notch on the outer edge of the steel insert.

8. The brake disc assembly according to claim 6 wherein each of said steel plates consists of a single annular ring having essentially the same inner and outer diameters as the beryllium core.

9. The brake disc assembly according to claim 6 where in three 120 arcuate steel plates form each annular ring, a beryllium core piece spanning the gap between adjacent steel plates, and the annular rings of steel plates having essentially the same inner and outer diameters as the beryllium core.

10. The brake disc assembly according to claim 6 wherein the angle between the one and second portions of the ends of the core pieces is 120, and the angular relation begins at approximately one third of the radial depth of the core pieces.

11. The brake disc assembly according to claim 6 wherein said steel plates and said core pieces are secured together by rivets passing through steel bushings in said core pieces, the ends of said bushings being cambered and said steel plates being formed in the region of said rivets to conform to the camber of said bushings, said bushings defining a projected area such that the torque loading into the core pieces falls between 1,000 p.s.i. to 6,000 p.s.i.

'12. The brake disc assembly according to claim 6 wherein the outer edges of said steel plates are notched in a gradually curved relationship between adjacent steel inserts to expose a portion of the sides of said core pieces.

13. The brake disc assembly according to claim 12 wherein the inclined angular relation between adjacent inserts and core pieces is between 50 to and the cooperating portion of adjacent edges equals at least 30% of the inclined distance.

References Cited UNITED STATES PATENTS 3,618,729 11/1971 Ely et al. 188-218 XL 3,403,759 10/1968 Holcomb, Jr. l88218 XL 2,330,856 10/1943 Adamson 192107 R X 2,835,367 5/1958 Steck 188251 R X 3,425,524 2/1969 Dewar 188218 XL 3,426,871 2/ 1969 Harnish 192-407 R 3,483,953 12/1969 Bender 188218 XL GEORGE E. A. HALVOSA, Primary Examiner US. Cl. X.R. 

